Russian Submarine

The RussianSubmarine was a nuclear submarine operated by Soviet Russia during the Cold War. While on a spying mission, it got sucked down into the Earth due to plate tectonics. This resulted in it getting stuck in the middle of a massive subterranean void. Will Burrows, Elliott, Chester, and Martha journey to the sub to collect medicines for the dying Elliott.

The Russian sub looks like a normal submarine, but has special powers. It ran on nuclear fuel and had torpedoes with nuclear warheads. Over the decades the fungus growing in Smoking Jean covered up most of the sub, so that only the conning tower could be seen.